Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
2000-04-03
2002-01-01
Duda, Kathleen (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S313000, C430S394000, C430S945000
Reexamination Certificate
active
06335146
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an exposure method and apparatus therefor, an exposure system and a mask circuit pattern inspection system, which eliminate an influence of interference light generated in an extremely fine circuit pattern formed on a mask, so that an image is formed with a high resolving power on a substrate through a projection lens and exposed and, further, wherein the light source is an excimer laser light source.
In the manufacture of an LSI, a circuit pattern on a mask is exposed and transferred onto a wafer to form a fine circuit pattern on the wafer. However, to cope with the need of high integration of LSI, the circuit pattern transferred onto the wafer tends to be an extremely fine pattern, which constitutes a resolution limit of an imaging optical system.
In view of the foregoing, various techniques have been developed in order to transfer an extremely fine circuit pattern.
For example, there is a method for exposure using X-rays such as SOR (Synchrotron Organized Resonance) light. There is a further method which uses an EB (Electron Beam) exposure machine. Furthermore, there is another method using an excimer laser disclosed in “Excimer Laser Stepper for Sub-half Micron Lithography, Akikazu Tanimoto, SPIE, Vol. 1088 Optical Laser Microlithography 2 (1989)” or Japanese Patent Laid-Open No. 57(1982)-198631.
A theoretical analysis of partial coherent imaging is introduced in “Stepper's Optics (1), (2), (3) and (4)” (Optical Technical Contact: Vol. 27, No. 12, pp. 762-771, Vol. 28, No. 1, pp. 59-67, Col. 28, No. 2, pp. 108-119, Vol. 28, No. 3, pp. 165-175).
Also, Japanese Patent Unexamined Publication No. 3-27516 describes an example in which a spatial filter is used to improve a resolving power.
Further, a phase shifter method for modifying a mask to improve a resolving power is known from Japanese Patent Publication No. 62(1987)-50811. According to this phase shifter method, light from a neighboring pattern is made to interfere, thereby enhancing the resolving power, which is realized by providing a film (a phase shifter) with phases alternately deviated through Π so that phases of adjacent patterns are inverted. However, the prior art known from the aforementioned Patent Publication No. 62(1987)-50811 has a problem in that an arrangement of the phase shifter is difficult, and the manufacture of a mask provided with the phase shifter is difficult.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an exposure method and an apparatus therefor so that an extremely fine white and black circuit pattern formed on a mask can be transferred onto a substrate with a resolving power equal to or higher than a phase shifter, while solving the aforementioned problem noted with respect to the prior art.
It is a further object of the present invention to provide an exposure method and system, and particularly an excimer exposure method and system, in which data of a transferred pattern on a substrate actually transferred by an exposure apparatus can be confirmed through simulation by arithmetic processing.
It is another object of the present invention to provide a mask circuit pattern inspection system in which even in the case where an extremely fine circuit pattern formed on a mask is different from a pattern transferred onto a substrate, the extremely fine circuit pattern formed on the mask can be inspected with high accuracy.
The aforesaid problem can be solved by the present invention which provides an exposure apparatus or exposure method comprising an illuminating arrangement, such as an excimer laser light source, having coherent property to a certain degree, an imager for imaging light in which a mask (including a reticle) illuminated by the illuminating arrangement is imaged onto a wafer, and a shield for shielding at least a part of the O-order diffraction light out of light which transmits through or reflects from the mask.
The present invention further provides an excimer exposure apparatus wherein a spatial filter shields an area corresponding to the NA of the illuminating arrangement.
Furthermore, the present invention provides an excimer exposure apparatus wherein the illuminating arrangement comprises an integrator and a spatial filter.
Moreover, the present invention provides an excimer exposure apparatus wherein the mask has a circuit pattern formed to have a line width which is substantially ½ of an imaging resolving power.
The present invention also provides a projection type exposure apparatus and method comprising an illuminating arrangement for substantially uniformly applying ring-like diffused illumination formed from a number of imaginary point sources to a mask in an exposure area, and a reduction projection lens having an optical eye which shields at least a part of the O-order diffraction light or low-order diffraction light out of light which transmits through the mask substantially uniformly diffused and illuminated by the illuminating arrangement and imaging a circuit pattern formed on the mask onto a substrate in the exposure area, wherein the circuit pattern formed on the mask is sequentially exposed on the substrate by step-and-repeat processing.
The present invention further provides an excimer exposure method which includes the steps of illuminating a mask formed with a circuit pattern, shielding at least a part of the O-order diffraction light out of light which transmits through or reflects from the circuit pattern of the illuminated mask, imaging the light by an imager, and transferring the imaged light onto a substrate.
Furthermore, the present invention provides an excimer exposure method wherein the minimum line width of the circuit pattern on the mask is formed by being suited to an imaging resolving power of the imager.
Moreover, the present invention provides an excimer exposure method wherein the mask has a circuit pattern formed to have a line width which is substantially ½ of the imaging resolving power.
The present invention further provides an excimer exposure method wherein the circuit pattern on the mask is formed to have a line width which is substantially ½ of the imaging resolving power, and in a wide circuit pattern when transferred onto a substrate, a transmission portion on the mask is formed of a line and space having a pitch of substantially ½ to ⅓ of the imaging resolving power or a lattice pattern.
The present invention further provides an excimer exposure method which includes the steps of dividing a circuit pattern formed on a mask into a fine pattern portion and a large pattern portion, imaging them by an imager and transferring the same onto a substrate.
The present invention also provides an excimer exposure system including a mask data converter for converting and producing data of a mask from data, and a calculator for applying arithmetic processing based on a transmission function substantially equivalent to an imager for transferring a circuit pattern formed on the mask using excimer laser light with respect to mask data obtained from the mask data converter to calculate data of the transferred pattern onto a substrate.
The present invention additionally provides a mask circuit pattern inspection system including a mask data converter for converting and producing data of a mask from wiring data, a calculator for applying arithmetic processing based on a transmission function substantially equivalent to an imager for transferring a circuit pattern formed on the mask using excimer laser light with respect to mask data obtained from the mask data converter to calculate data of a transferred pattern on a wafer, an inspection device including an illuminating arrangement for illuminating a mask with the excimer light, an imager for imaging light which transmits through or reflects from a mask illuminated by the illuminating arrangement to a detection position, the imager having a transmission function substantially equivalent to that of the first-mentioned imager, and a light receiver for receiving an imagi
Kenbo Yukio
Murayama Makoto
Noguchi Minori
Oshida Yoshitada
Shiba Masataka
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